X-ray apparatus



May 29, 1956 M. E. HAYES ET AL 2,748,287

X-RAY APPARATUS Filed Jan. 25, 1955 3 Sheets-Sheet 5 TB+ I X-RAY APPARATUS Martin E. Hayes, Severn Heights, and Kenneth A. Kiesel, Catonsville, Md, assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application January 25, 1955, Serial No. 483,932

10 Claims. (Cl. 250-65) The present invention relates to X-ray apparatus, and more particularly to a position control apparatus for the control of certain of the X-ray apparatus components relative to others of said components.

In the use of X-ray apparatus where the proper positioning of an X-ray responsive device such as a film relative to the X-ray source such as the X-ray tube is important, there is a considerable problem in assuring that the central ray from the X-ray source coincides with the center line of the film member. The problem is comparatively easy where the operator is located such that the film or film holder is visible. However, when the film is located below and within an enclosing table, such as in the receiving tray of a bucky diaphragm or like device, the operator can not visibly position the film relative to the X-ray source and accordingly additional apparatus and methods are necessary to accomplish this desired purpose.

Accordingly, it is an object of the present invention to provide an improved X-ray apparatus such that the X-ray source can be maintained in a predetermined and desired position relative to the film holder or like member.

It is another object of the present invention to provide apparatus for controlling the position of the X-ray source relative to the film holder.

It is a different object of the present invention to provide X-ray apparatus operative to provide a position error signal for controlling the position of the X-ray source relative to the X-ray receiving member or film.

It is another object of the invention to provide an automatic control for one component of the X-ray apparatus dependent upon the condition of another component of the apparatus.

It is an object to provide X-ray apparatus including a manually positioned first component and a control which will correspondingly position a second component of the apparatus.

These and other objects of the invention are elfected as will become apparent from the following description taken in accordance with the accompanying drawings, which form a part of this application and, in which:

Figure 1 shows a schematic diagram of the circuit and apparatus of the present invention;

Fig. 2 shows a top plan view of apparatus in accordance with the present invention;

Figs. 3 and 4 illustrate the use of the comparison signals in accordance with the present invention; and

Fig. 5 shows a schematic diagram of a suitable comparator circuit.

In Fig. 1 there is shown an X-ray table including a tubestand 12. The tubestand is movable along a rail 14 relative to the X-ray table 10 by means of a tubestand motor 16. A support roller or like member 18 is provided for the tubestand which roller is connected to a tubestand position potentiometer 20, such that the latter potentiometer is moved in proportion to the movement of the tube- Patented May 29, 1956 stand 12. The tubestand supports an X-ray tube or X-ray source 22, such that the angular position of the X-ray source 22 can be changed relative to the X-ray table 10.

Within the table 10 there is positioned a bucky or like X-ray diaphragm 24 which is operative as a support or holder for X-ray film or a similar X-ray responsive member. A support roller 26 is provided for the bucky diaphragm such that a connecting belt or like member 36 is operative with the roller 26 to control the operation of a bucky position potentiometer 32 which is connected to the latter roller 26. An X-ray source position potentiometer 34 is connected to the X-ray source 22 such that the latter potentiometer 34 is moved in accordance with the angular position of the source 22.

The X-ray source 22 can also be moved in a vertical direction along the tubestand 12 and relative to the X-ray table 10 by means of a support roller 36, which latter support 36 is connected to a tube height position potentiometer 38 such that the latter potentiometer 38 is moved proportional to the movement of the X-ray source 22 in a direction along the tubestand 12 and substantially perpendicular to the X-ray table 10 as shown. The X-ray source position potentiometer 34 is connected across the secondary winding 40 of a transformer 42, having a primary winding 44 connected to a suitable source of potential 46 through a control switch 48. The secondary winding 40 has a center tap connection 50 which is grounded. The X-ray source position potentiometer 34 has a center connection 52 which is grounded. The latter potentiometer 34 has a movable arm member 54 connected across the tube height potentiometer 38 and then to ground potential. The latter potentiometer 38 has a movable arm 56 which is connected through resistor 58 and diode rectifier tube 60 to the input of a comparator circuit 62. The output of the latter comparator circuit 62 is connected to ground potential through the tubestand control motor 16. The movable arm member 64 of the bucky diaphragm position potentiometer 32 is connected through a resistor 66, a switch member 68 and a diode rectifier tube 70 to the input of the comparator circuit 62. A second transformer 72 is provided having a primary winding 74 which is connected across the suitable source of voltage 46. The transformer 72 includes a secondary winding 76 having a grounded center tap connection 78, such that a first half of the secondary winding 76 is connected across the tubestand position potentiometer 20 to ground and across the bucky diaphragm position potentiometer 32 to ground. A second half of the secondary winding '76 is connected through a standard or reference resistor 80 to ground potential. The latter resistor 80 has a movable arm 82 which is connected through a diode rectifier 84 to the input of the comparator circuit 62. A horizontal cassette changer 86 is shown including a control switch 88 having a movable arm 20 and three switch positions 92, 94, and 96, with each of the latter switch positions being provided for setting the distance between the tubestand and the horizontal cassette changer, as desired. The first switch position 92 is connected to a tap 98 on the suitable dropping resistor 169. The second switch position 94 is connected to a tap 102, and the third switch position is connected to a tap 194, with the dropping resistor 100 being connected between one half of the secondary winding 76 and ground potential.

In Fig. 2, there is shown the tubestand 12, the tube stand control motor 16, the tubestand support roller 18, the tubestand position potentiometer 2t) and the X-ray source height potentiometer 38 which is connected to the X-ray source support roller 36. The support arm 106 for the X-ray source (not shown in Fig. 2) is illustrated as connecting from the tubestand 12 to a position above the X-ray table 10. The bucky or X-ray diaphragm mem- 3 ber 24 is shown connected to the diaphragm support roller 26 by means of the connecting cable 30, and the diaphragm support roller 26 is shown connected to the diaphragm position potentiometer 32. The film or X-ray receiving member 103 is shown supported by the X-ray diaphragm 24.

Referring to Figs. 3 and 4 there are shown the composite signals as applied to the input of the comparator circuit 62 shown in Fig. 1. The alternate pulses 110 have a magnitude set by the position of the standard reference potentiometer 80. The alternate pulses 112 have a magnitude corresponding to the combined positions of the X-ray diaphragm and the X-ray source. When the diaphragm and X-ray source are in line the combined signal produced by the positions of potentiometers 32 and 20 cause the pulses 112 to be equal to the pulses 110.

Potentiometers 32 and 20 are connected in reverse to each other so to speak. If the diaphragm is moved to the left the resistance is increased while if the X-ray source (tubestand) is moved to the left the resistance is decreased. in this way if the movement of the diaphragm causes an increase in the resistance of 32, the alternate pulses 112 would become larger than the pulses lit). The tubestand would move towards the diaphragm and its potentiometer 20 would decrease in resistance and reduce the magnitude of pulses 112 until such time as pulses 11% and 112 were equal. The alternate pulses 110 have a first magnitude for a reference standard and are determined by the adjustment of the standard reference potentiometer 80. The remaining alternate pulses 112 have a second magnitude corresponding to the position of the X-ray source 22 and the X-ray diaphragm 24.

In the illustrations of Figs. 3 and 4, the magnitude of the first set of alternate pulses 110 is difierent than the magnitude of the second set of alternate pulses 112. This is due to the position or" the X-ray diaphragm not corresponding to the position of the X-ray source. When the positions of the X-ray source and X-ray diaphragm substantially correspond and they are substantially aligned, the one set of alternate pulses 110 will have substantially the same magnitude as the other set of alternate pulses 112.

in the operation of the apparatus shown in Fig. 1, the tubestand 12 is movable by means of control motor 16 along the rail 14 and relative to the X-ray table such that the X-ray source 22 supported by the tubestand 12 can be moved to any desired position relative to the patient or object to be X-rayed on the X-ray table 10. Within the X-ray table 10 and in position to be subjected to the X-rays from the X-ray source 22 there is positioned an X-ray diaphragm 24 containing or including an X-ray receiving member or film. In one embodiment of the present invention the X-ray diaphragm 24 is adapted for manual movement by means of an operator and the disclosed circuit is operative to position the tubestand 12 such that the X-ray source 22 carried by the latter tubestand 12 is properly positioned such that the center line of the film held by the X-ray diaphragm 24 is in the desired relationship relative to the central ray from the X-ray source 22. In this respect the comparator circuit 62 is operative to control the motor 16 to move the tubestand along the rail 14 in either direction relative to the X-ray table 10.

The bucky or X-ray diaphragm 24 may be initially moved manually by the operator to the desired position relative to an object or patient to be X-rayed. This movement of the X-ray diaphragm 24 causes the diaphragm position potentiometer 32 to be operative to introduce a signal proportional to the position of the X-ray diaphragm 24 into the input of the comparator circuit 62 through the resistor 66 and the diode rectifier 60, the switch member 68 and the rectifier 70.

The latter voltage or signal is then compared by the comparator circuit 62 with the standard or reference signal applied to the input of the comparator circuit 62 by means of the standard adjustment resistor and the diode rectifier $4. Still another signal is received from the X-ray source position potentiometer 34 and the X-ray source height potentiometer 38, which are series connected to provide an additive or combination signal proportional to the respective angular position of the X-ray source 22 and the height position of the X-ray source 22 relative to the X-ray table Kit. This latter voltage or signal is applied through a resistor 58 and diode rectifier 69 to the input of the comparator circuit 62. The tubestand position potentiometer 24 is operative to provide a signal which is proportional to the position of the tubestand 12 relative to the X-ray table 10 such that this signal can be applied through the resistor 55 and the diode 7t) to the input of the comparator circuit 62.

Applicants have chosen to apply alternating current voltages across the potentiometers 32, 34, 20, 38 and St and by means of the diode rectifiers 6t), 76 and 84 have provided half way rectified signals such that the comparator circuit 62 may be of the difference amplifier type and operative as an alternating amplifier. The signal received from the diaphragm position potentiometer 32 and the signal received from the tubestand position potentiometer 20 are in effect added or combined and rectified by diode rectifier '70 before being applied to the input of comparator circuit 62 to provide the pulses 112. The signals from the diaphragm position potentiometer 32 and the tubestand position potentiometer 20 have a first polarity opposite to the polarity of the signal received from the series connected X-ray source position potentiometer 34 and X-ray source height potentiometer 38. Accordingly, the voltage pulses 112 as shown in Figs. 3 and 4 have an amplitude corresponding to the difierences between the latter signals. The pulses as shown in Figs. 3 and 4 correspond to the standard reference pulses received from the standard adjusted resistor 80 and diode rectifier 84.

With regard to the diaphragm position potentiometer 32 and the tubestand position potentiometer 20, these potentiometers are connected in series and respectively opposite, such that for example a movement of the diaphragm to the left would cause the resistance value of the diaphragm position potentiometer 32 to increase, and a correcting movement of the tubestand 12 to the left would be necessary with a corresponding decrease in the series resistance value of the tubestand position potentiometer 20. In other words, for example, a left movement of the diaphragm 24 would cause the magnitude of the pulses 112 to be larger than the pulses 110, and a corresponding movement of the tubestand 12 to the left would equalize the magnitude of the pulses 112 relative to the pulses 110.

The comparator circuit 62 may be of the ditference amplifier type and is operative to compare a composite unknown signal with a known standard signal. The composite unknown signal is made up of signals received from, respectively, the diaphragm position potentiometer 32, the tubestand position potentiometer 20 and the series connected X-ray source height potentiometer 38 and X-ray source angular position potentiometer 34. The known and standard signal is received from the standard adjustment resistor 80 through the diode rectifier 84. If the composite unknown signal and the standard signal are equal in amplitude, the "comparator circuit 62 cffectively balances and the tubestand control motor 16 is not energized to change the position of the tubestand 12. Should the unknown signal 112 as shown in Fig. 3 be larger than the reference signal 110, the control motor 16 is energized to move the tubestand 12 in a direction to equalize the latter signals. If the unknown signal 112 is smaller than the standard signal 110 as shown in Fig. 4, the control motor 16 is energized to equalize assess? these signals. The comparator circuit 62 thus compares the unknown signal and the standard signal which are 180 degrees out of phase with each other due to the connection of secondary winding 76.

If the X-ray source 22 is positioned such that the center ray from the X-ray source 22 is substantially perpendicular to the X-ray diaphragm 24, then effectively the difference between the output signals of the tubestand position potentiometer 20 and the diaphragm position potentiometer 32 only is compared to the standard reference signal received from the standard or reference resistor 80. However, if it is desired that the X-ray source 22 be employed at some angular position, as shown in Fig. 1, relative to the direction in which the tubestand effectively extends away from the table 10, then the displacement of the X-ray source 22 is a function of the height of the X-ray source 22 and the tangent of the angular position of the X-ray source 22 relative to the plane of the X-ray diaphragm 24 or the plane of the top of the X-ray table 10 as illustrated. In this respect the X-ray source position potentiometer 34 is operative to provide an output signal or voltage proportional in magnitude and having a polarity corresponding to the angular position of the X-ray source 22. The transformer tap 50 is grounded as is the connection 52 of the X-ray source position potentiometer 34 corresponding to the central or perpendicular position of the central ray from the X-ray source 22. The potentiometer 34 comprises a first half including a plurality of taps 114, 116, 118 and 120 corresponding to predetermined angular positions of the X-ray source 22 that may be to the right of the position when the central ray is perpendicular to the X-ray table 10, and taps 122, 124, 126 and 128 correspond to similar predetermined angular positions to the left of the central position. The output voltage from the X-ray source position potentiometer 34 is applied across the X-ray source height potentiometer 38 to provide an output voltage which is a function of and proportional to both the angular position of the X-ray source and the height position of the X-ray source.

By means of the selector switch 68 the apparatus shown in Fig. 1 is operative to automatically determine the distance between the X-ray source 22 and a horizontal cassette changer member 86. In normal practice three distances are employed, either 36 inches, 48 inches or 72 inches. By means of the selector switch 68, a voltage or signal corresponding to one of these distances may be substituted for the diaphragm position signal otherwise received from the potentiometer 32, such that the circuit of Fig. 1 is operative to so position the X-ray source 22 relative to the cassette changer member 86.

A suitable schematic diagram of the comparator circuit 62 shown in Fig. 1 is shown in Fig. 5. Electron devices 120 and 122, with their plate load resistors 124 and 126 and cathode resistor 128 are connected in a balanced bridge type of amplifier circuit. The cathode resistor 128 is used to balance the circuit. A polarized relay member 130 is connected between the plate electrodes of the electron devices 120 and 122. The movable contact arm 132 of the relay member 130 can be moved in a first direction to connect with a first contact member 134 or in a second direction to connect with a second contact member 136. The reversible tubestand motor 16 is shown connected between a suitable potential source 138 and the first contact member 134 and second contact member 136, such that when the contact arm 132 moves to connect with the first contact member 134 the tubestand motor 16 moves in a first direction and when the contact arm 132 connects with the other contact member 136 the motor 16 moves in the opposite direction.

When the comparator circuit shown in Fig. is balanced the plate currents of the electron devices 120 and 122 are substantially equal, and the voltage drops across the plate resistors 124 and 126 are substantially equal. At this time no current will flow in either of the relay control windings 140 and 142 and the contact arm 132 will remain in the neutral or central position.

The input signal to the comparator circuit, corresponding to the signal wave forms shown in Figs. 3 and 4, is applied between connecting leads 144 and 146, and across resistor 145 and is impressed on the control grids 148 and 150 of the electron devices 120 and 122. The screen grids 152 and 154 of the latter devices 120 and 122 are connected to the opposite ends of a center-tapped secondary winding 156 of transformer 158. The primary winding 160 of the latter transformer is connected to a suitable alternating voltage source, which may correspond to source 138. Accordingly electron device 120 is made to conduct during a first half cycle of the voltage from source 162 and the other electron device 122 is made to conduct during the second half cycle of the same voltage. The input signal is thereby separated in that electron device 120 conducts to pass the first set of pulses 110 and the other electron device 122 conducts to pass the second set of pulses 112. When the first pulses 110 are equal to the second pulses 112, both electron devices 120 and 122 conduct equally and the contact arm 132 of the relay member 130 remains in the central position. If the first pulses 110 are larger, the contact arm 132 moves in a first direction to energize the motor 16 to move in a first direction to equalize the two sets of pulses, and if the second pulses 112 are larger the contact arm 132 moves in the opposite direction and motor 16 moves in the opposite direction to equalize the two sets of pulses. The motor 16 is connected to drive the tubestand in n e necessary direction to align the central ray from the X-ray source 22 with the center line of the diaphragm member 24. 7

Accordingly, the comparator circuit shown in Fig. 5 is operative to compare the first pulses 110 with the second pulses 112 and causes relay member 131) to be energized to move motor 16 to correct for any difference between the first pulses 110 and second pulses 112. The second pulses 112 will be either larger or smaller than the first pulses 110 when the central ray from the X-ray source 22 is to the right or to the left of the center line of the diaphragm 24.

While We have shown a preferred embodiment of our invention, it will be obvious to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention.

We claim as our invention:

1. In X-ray apparatus including an X-ray source and an X-ray responsive member, the combination of an X-ray diaphragm fastened to said X-ray responsive member, a tubestand fastened to said X-ray source, tubestand position responsive first means having an output signal proportional to the position of said tubestand, 21 diaphragm position responsive second means having an output signal proportional to the position of said diaphragm, and control means responsive to the output of said first means and the output of said second means for maintaining a predetermined relationship between the position of said diaphragm and the position of said tubestand.

2. In X-ray apparatus including an X-ray source and an X-ray picture member, the combination of a first sup port for said X-ray source, a second support for said picture member, a first source of a first voltage proportional to the position of said X-ray source, a second source of a second voltage proportional to the position of said picture member, and a control connected to said first source and to said second source for controlling the relative position of the X-ray source as compared to the position of the picture member.

3. In X-ray apparatus including an X-ray source and an X-ray picture member, the combination of a first support for said X-ray source, a second support for said picture member, a source of a first voltage proportional to the position of said first support, a source of a second voltage proportional to the position of said second support,

and a comparison control circuit for comparing said first voltage and said second voltage to control the relative position of said first support as compared to the position of said second support 4. The apparatus of claim 3, characterized by said first voltage having a first polarity and said second voltage having a second polarity, with said comparison control circuit being operative to determine the difference between said first voltage and said second voltage.

5. The apparatus of claim 2, including a motor member for moving said first support, with said motor member being connected to said control and being operative to move the position of said X-ray source.

6, The apparatus of claim 2, with said first source comprising a potentiometer connected to said first support to be operated by the movement of said first support and with said second source comprising a potentiometer connected to said second support and operative by movement of said second support.

7. The apparatus of claim 3, including a reversible motor member for said first support, With said motor member being connected to said comparison control and operative for moving said first support in either a first direction or a second direction.

8. In X-ray apparatus including an X-ray source and an X-ray picture member, the combination of a first support member for said X-ray source, With the latter X-ray source being pivotally connected to said first support member, a second support member for said X-ray picture member, a first source of a first voltage proportional to the angular position of said X-ray source relative to said first support member, a second source of a second voltage proportional to the position of said picture member, and a comparison control circuit connected to said first source and said second source for comparing said first voltage to said second voltage and for controlling the position of said X-ray source relative to the position of said picture member.

9. The apparatus of claim 8 including an X-ray table, said first support member extending substantially in a first direction relative to said X-ray table, and a third source of a third voltage proportional to the distance of said X- ray source from said table in said first direction, with 'said comparison control circuit being connected to said third source.

10. In X-ray apparatus including an X-ray source and an X-ray picture member, the combination of a tubestand For supporting said X-ray source, an X-ray diaphragm for supporting said picture member, a first potentiometer connected to said tubstand for providing a first voltage proportional to the position of said tubestand, a second potentiometer connected to said X-ray diaphragm for providing a second voltage proportional to the position of said diaphragm, and a control circuit connected to said first potentiometer and said second potentiometer for controlling the relative position of said tubestand as compared to the position of the X-ray diaphragm.

No references cited. 

